Achieving high levels of reading proficiency in the deaf population has resisted our best efforts in both research and practice [1]. Progress in this area is limited by the lack of basic science research that focuses on deaf readers. In particular, we know almost nothing about syntactic processing of English in deaf readers. The immediate goal of the proposed research is to uncover basic facts about on-line processing and comprehension of English sentences in this population. The long-range goal is to use this knowledge to design more effective materials and methods to enhance literacy. Thus, the proposed research furthers NIH's mission of seeking fundamental knowledge about the nature and behavior of living systems and applying that knowledge to enhance health and reduce the burdens of illness and disability. The specific aims of the project include the following: (1) to investigate the effects of syntactic complexity on processing time and comprehension in deaf readers; (2) to investigate how individual differences moderate the effects of syntactic complexity on processing time and comprehension. The proposed experiments manipulate syntactic properties of English sentences and measure the effects of those manipulations on patterns of eye-movements during reading. Comprehension outcomes are also assessed. We will contrast performance in deaf readers, hearing Chinese-English bilingual readers who have English as a second language, and hearing native English readers. The chief dependent measures will be fixation times and responses to comprehension questions. These data will allow us to determine how much difficulty deaf readers have processing and interpreting sentences of different syntactic types. In addition to collecting outcome data, we will collect demographic data and indices of individual skills and knowledge, including executive function, working memory capacity, English vocabulary, and oral communication ability. We will apply mulitilevel modeling techniques [9, 69] to assess how individual reader characteristics and text characteristics interact to determine processing and comprehension outcomes. The results of the proposed experiments will have implications for psycholinguistic theories of syntactic processing in deaf and hearing bilinguals and will extend the investigation of individual differences in sentence processing among hearing native English speakers. The results of these experiments will inform the design of further experiments investigating sentence processing in deaf readers. The knowledge gained from these experiments will inform efforts to construct improved materials and methods for developing literacy skill in deaf readers. The findings may also have relevance for problems in hearing readers that relate to phonological processes.